oil boiler run out of oil 3 months ago filled tank up and bled the boiler and started it and was fine until we filled the tank again 3 days ago and when the boiler started it gave black smoke and kept smoking through the flue ,called a plumber and he cleaned the sot out and changed the nozel with the filter but still didnt fire up proply and he said the transformer has gone ,because we bled it 3 months ago and we altered the pressure of the pump although it was running fine.and now to fix it is going to cost us over £200 pounds .is what he said right?